Well, Corona 1.0 has GGX, which makes using blended materials for as elementary things as plastic obsolete. The blending method was only to fake the tail falloff of more sophisticated BRDFs. There is no reason to do that thing with GGX. Actually, there was no reason to do that thing even with ashikhim-shirley BRDF corona used previously. There was reason to do that only with VrayMTL, because it used really, i mean really cheesy and terrible Blinn BRDF.
So doing these stunts will only rarely make your materials look better, but it will definitely make them render a lot slower ;)